A very difficult question. First, the investigators have to find all the mutations and DNA changes that predispose to MH. This is a laborious process since there are several genes that predispose to MH, although changes in the ryanodine receptor gene probably underlie about 70% of cases. Another gene identified as predisposing to MH is the DHPR gene, also related to muscle function. In addition, there are probably over 60 mutations in the RYR-1 gene that are causal for MH, although causality has been proven for only about 30 DNA changes. In order to prove that a DNA is causal, either families must be identified where DNA change pattern is consistent with biopsy proven susceptibility or, in the laboratory, the DNA change must be incorporated in cultured muscle cells, and the calcium release in the cell under the influence of caffeine or halothane must show changes found in MH.